Answer:
29.0 g
Explanation:
We know that we will need a chemical equation with masses and molar masses, so let’s start by gathering all the information in one place.
[tex]M_{r}[/tex]: 63.55 46.01
Cu + 4HNO₃ ⟶ Cu(NO₃)₂ + 2NO₂ + 2H₂O
Mass/g: 20.0
1. Use the molar mass of Cu to calculate the moles of Cu.
[tex]\text{Moles of Cu} = \text{20.0 g Cu}\times \frac{\text{1 mol Cu} }{\text{63.55 g Cu}}= \text{0.3147 mol Cu}[/tex]
2. Use the molar ratio of NO₂:Cu to calculate the moles of NO₂.
[tex]\text{Moles of NO}_{2} = \text{0.3147 mol Cu} \times \frac{\text{2 mol NO$_{2}$}}{\text{1 mol Cu}} = \text{0.6294 mol NO}_{2}[/tex]
3. Use the molar mass of NO₂ to calculate the mass of NO2.
[tex]\text{Mass of NO}_{2} = \text{0.6294 mol NO$_{2}$}\times \frac{\text{46.01 g NO$_{2}$} }{\text{1 mol NO$_{2}$}}= \text{29.0 g NO}_{2}[/tex]
